In order to prevent severe flooding from heavy rains or melted snow, most municipalities have built underground drainage systems. Water flows into the underground drainage basin by passing through a basin grate, usually placed on one side of a road, before it is released into an underground sewer line. Such basin grates are often provided with an overflow slot which receives the runoff and directs it to the sewer system when the runoff is at a greater rate than the catch basin can handle.
Ideally, the water entering the drainage basin should be free of any solid debris or other environmental contaminants. Such solid debris and environmental contaminants can cause blockage in the system which can result in flooding as well as causing damage to the basin and sewer line if allowed to pass through freely.
In addition, recent state and federal legislation has required a reduction in water pollution and debris and dirt in the runoff. One source of water pollution is the solid debris and environmental contaminants which are carried by the flow of water to, and released into drainage basins. A great deal of particulate matter can be picked up for instance when a source of the water is in an area in which the ground has been disturbed, such as is the case at most construction sites. Consequently, many governmental agencies are requiring developers to provide some means of preventing the runoff which enters the drainage system from carrying with it debris and particulate matter.
In order to filter the runoff that enters a drainage basin at construction sites, filters have been placed, usually above ground, around the grate of the drainage basin. Not only are these devices an eyesore, but they also tend to greatly impede the flow of water into the drainage basin because of either the debris which the filter collects or the filter itself. Such impedance could cause the exact flooding which these basins are meant to prevent. Underground basin filters such as that disclosed in U.S. Pat. Nos. 5,575,925 and 5,372,714 solve some of these problems but they do not include a means of filtering the water which enters the drainage system through the overflow slot.
U.S. Pat. No. 5,632,888 discloses a catch basin filter which includes means for filtering water flowing through the overflow slot but the filter shown in the patent is different to install and to remove for cleaning or replacement.
There exists a need then for an underground filter which can be easily manufactured and which can be readily mounted in place to separate and prevent solid debris from entering a drainage basin, not permitting any portion of the water flow to enter the drainage basin either through the grate or the overflow slot without passing through the filter.